I tell my GF something similar, she f**king is meant to work til 9-5 Mon-Fri...She stays til like 1830 every night. It makes me angry, she complains about it but doesn't do anything about it!

I keep telling her if she doesn't do something about it then nothing will happen. She says 'Everyone else does the same'. I don't give a f**k, you are you not being paid to work til half 6 each night.

Once in a blue moon is probably an acceptable part of your industry. But if it happen often say something, make stuff change.